JP2939151B2 - Fluorescent display tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent display tube (VFD:
Vacuum Fluorescent Display), and more particularly, to a technique for improving display pattern density.

[0002]

2. Description of the Related Art Phosphor layers corresponding to emission patterns are respectively fixed on a plurality of anodes provided on a display surface of a substrate, and electrons generated from a cathode located above the display surface in a vacuum space are generated. 2. Description of the Related Art A fluorescent display tube of a type in which a phosphor layer selectively emits light by colliding with the phosphor layer is known. In such a fluorescent display tube, the operating voltage is low and the display is clear because the surface of the phosphor layer on which electrons generated from the cathode collide is located on the display side, and phosphor layers with different emission colors are prepared. This makes it possible to perform color display, and is often used as a display component for audio equipment and dashboards of automobiles.

[0003] In one kind of the above-mentioned fluorescent display tubes, the phosphor layer is replaced with a mesh-like grid for controlling light emission of the phosphor layer on a plurality of anodes provided on the display surface of the substrate. A rib-like wall protruding from the periphery of the anode of the substrate so as to surround it and a grid electrode provided on the top of the rib-like wall are provided, and the grid electrode positioned higher than the phosphor layer is provided on the phosphor layer. A type in which light emission is controlled has been proposed. For example, a fluorescent display tube described in Japanese Patent Application Laid-Open No. Sho 62-290050 is that.

In the above-mentioned fluorescent display tube, thermoelectrons emitted from a filament functioning as a cathode are applied to a grid electrode located at the top of a rib-like wall by a relatively low-pressure positive acceleration voltage of about several tens of volts. Thereby, the phosphor layer is accelerated and collided toward the phosphor layer located on the anode, so that the phosphor layer surrounded by the grid electrode emits light, so that dynamic driving is preferably performed. According to the fluorescent display tube of this type, since a mesh-shaped grid is not used, uneven brightness or short-circuit caused by thermal deformation of the grid when the emission pattern of the phosphor layer is enlarged as the size becomes larger. There is an advantage that display defects such as the above are eliminated, and that the brightness of the fluorescent display tube is reduced in relation to the aperture ratio of the mesh grid.

[0005]

By the way, when dynamic driving is performed with the above-mentioned conventional fluorescent display tube, when a positive acceleration voltage is applied to one of the plurality of grid electrodes, A negative erase voltage (cutoff bias) is applied to all other grid electrodes. Therefore, the trajectory of the thermoelectrons directed to the phosphor layer surrounded by the grid electrode to which the acceleration voltage is applied is distorted due to the negative electric field formed by the erase voltage applied to the adjacent grid electrode. As a result, there is a problem that light emission unevenness may occur in a part of the phosphor layer located near the boundary with another grid electrode.

Therefore, the applicant of the present application has previously filed Japanese Patent Application No.
No. -164373 in (unpublished) and the like, as shown in FIG. 4, a further outer peripheral side of the grid electrode 22 surrounding each phosphor layers 20 _S, one or a plurality of auxiliary grid electrode 50 surrounds the grid electrode 22 is provided The proposed fluorescent display tube was proposed. According to this technique, since the grid electrodes surrounding each phosphor layer 20 _S have a multi-layer structure, the adjacent grid electrodes 2 S
Becomes a negative electric field due to the negative erase voltage applied to 2 are canceled by the auxiliary grid electrode 50 located on the outer peripheral side, uneven light emission of the phosphor layer 20 _S is suitably suppressed. The number of the auxiliary grid electrodes 50 of the fluorescent display tube is determined by the accelerating voltage and the erasing voltage of the grid electrode 22. If necessary, one or a plurality of auxiliary grid electrodes 50 (i.e., one to several grid electrodes 22 are used). The grid electrode 2 surrounding each phosphor layer 20 _S
2 are connected to each other by the connection electrode 52 and driven together with the grid electrode 22, and when the erase voltage is applied to the grid electrode 22, the erase voltage is similarly applied.

However, in the above-mentioned fluorescent display tube,
Since an auxiliary grid electrode is provided for each grid electrode, a pair of auxiliary grid electrodes surrounding each are provided between adjacent grid electrodes. Therefore, as shown in FIG. 5 which is a cross-sectional view taken along the line VV of FIG.
When the number of auxiliary grid electrodes 50 for surrounding the electrode is n, the width is W, and the interval between the electrodes is D, each grid electrode 2
The interval d between 2, 22 is [2nW + (2n + 1) D] (where n ≧ 1; n = 1 in the figure), which is a relatively large value, and there is a problem that the light emitting pattern interval is relatively large. . However, considering the dynamic driving of the fluorescent display tube, as described above, one grid electrode 22 is used.
When the accelerating voltage is applied to all the grid electrodes 22, the erasing voltage is applied to all the other grid electrodes 22, and the auxiliary grid electrode 50 to which the voltage is applied at a time is provided between the adjacent grid electrodes 22, 22. Only those surrounding one grid electrode 22 of the 2n grids (that is, n grids)
Becomes In other words, the number of auxiliary grid electrodes 50 to which a voltage is applied at one time is the number required to actually suppress the uneven emission, and in consideration of this, the number of auxiliary grid electrodes 50 is twice as large as the required number. It can be thought that it is.

The present invention has been made based on the above findings, and an object thereof is to provide a fluorescent display tube in which a grid electrode is provided on the top of a rib-like wall surrounding a phosphor layer. An object of the present invention is to reduce a light emitting pattern interval without causing unevenness.

[0009]

In order to achieve the above object, the gist of the present invention is to provide a phosphor layer having a shape corresponding to a light emission pattern on a plurality of anodes provided on a display surface of a substrate. And a rib-like wall protruding above the phosphor layer is provided at a position surrounding the phosphor layer, a grid electrode is provided at the top of the rib-like wall, and a grid electrode is provided above the display surface in a vacuum space. In a fluorescent display tube of a type in which a predetermined phosphor layer emits light by controlling electrons generated from a located cathode by its grid electrode, (a) a height similar to that of the rib-shaped wall is provided on the outer peripheral side of the rib-shaped wall. The auxiliary rib-shaped wall is protruded, and an auxiliary grid electrode to which a predetermined acceleration voltage is applied independently of the grid electrode is provided at the top of the auxiliary rib-shaped wall.

[0010]

According to this structure, a grid electrode is provided on the display surface of the substrate at a position surrounding the phosphor layer and on the top of the rib-like wall protruding higher than the phosphor layer. Light emission of the phosphor layer is controlled. At this time, in order to cancel the negative electric field generated by the grid electrode to which the erasing voltage is applied and suppress the uneven emission, the auxiliary grid electrode provided on the top of the auxiliary rib-like wall provided on the outer peripheral side of the rib-like wall has , A predetermined acceleration voltage is applied independently of the grid electrode. Therefore, the auxiliary grid electrode provided between the adjacent grid electrodes is configured to cancel the negative electric field generated by the other grid electrode to which the erase voltage is applied, even when the acceleration voltage is applied to any of the grid electrodes. Works.

[0011]

As described above, the auxiliary grid electrodes provided between adjacent grid electrodes serve as auxiliary grid electrodes common to those grid electrodes, so that the grid electrodes are individually driven together with the grid electrodes. It is no longer necessary to provide auxiliary grid electrodes to be provided, and the number of auxiliary grid electrodes provided between the grid electrodes is reduced to the minimum number necessary to cancel the negative electric field generated by the grid electrode to which the erasing voltage is applied (ie, Conventional 1 /
2). Therefore, the distance between adjacent grid electrodes required to provide the auxiliary grid electrode and suppress the uneven emission is [nW + (n + 1)].
D], without causing uneven light emission.
It is possible to obtain a fluorescent display tube capable of reducing the light emission pattern interval.

That is, as described above, in a conventional fluorescent display tube having auxiliary grid electrodes, the auxiliary grid electrode is driven along with the grid electrodes, so that the acceleration voltage is applied to any of the grid electrodes. In order to suppress light emission unevenness even when voltage is applied, it is necessary to provide an auxiliary grid electrode for each grid electrode. However, according to the above, the auxiliary grid electrode is a grid surrounding each phosphor layer. Since they are independent of the electrodes, the number of lines required for suppressing uneven light emission can be reduced. Note that even if a predetermined acceleration voltage is applied to the auxiliary grid electrode, the erase voltage is applied to the grid electrode surrounding the phosphor layer that does not emit light. Erroneous light emission of the phosphor layer does not occur.

Preferably, (b) the auxiliary rib-like wall is provided so as to surround the rib-like wall, respectively, and (c) the auxiliary grid electrode provided on the top of the auxiliary rib-like wall is , Connected to a common auxiliary grid wiring. In this case, the number of independent wirings and electrodes is minimized as compared with the conventional fluorescent display tube having the auxiliary grid electrode, so that the wiring and the driving circuit are prevented from becoming complicated.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a partially cutaway perspective view of a fluorescent display tube 10 according to one embodiment of the present invention. In the figure,
The fluorescent display tube 10 includes a substrate 12 made of an insulating material such as glass, ceramics, or enamel having a plurality of phosphor layers 20 _S , 20 _D , and 20 _N described below formed in a predetermined light emitting pattern at a plurality of positions, and a frame. Glass spacer 14 formed in a shape
, A transparent cover glass plate 16 and a plurality of anode terminals 1
8 _P , a plurality of grid terminals 18 _G , cathode terminals 18
_K , and an auxiliary grid terminal 18 _SG, and the substrate 12, the spacer 14, and the cover glass plate 1 are provided.
6 are sealed with each other by glass to form a vacuum space surrounded by these members.

The surface of the substrate 12 covered by the vacuum space functions as a display surface of the fluorescent display tube 10. The substrate 12 includes a plurality of phosphor layers each having a seven-segment "8" character shape. 20 _S , one phosphor layer 20 _D representing a dot shape, and one phosphor layer 20 _N representing a “1” character shape
Is arranged. The respective phosphor layers 20 _S , 20 _D ,
20 _N are each surrounded by a grid electrode 22, and the grid electrode 22 is further surrounded by a common auxiliary grid electrode 24 on the entire surface of the fluorescent display tube 10.
Of the above-mentioned phosphor layers 20 _S , 20 _D , and 20 _N , those having a predetermined position for each display digit are connected to each anode terminal 18 _P via an anode printed wiring 34 described later. Each of the grid electrodes 22 is connected to the grid wiring 2.
6, each is connected to each grid terminal 18 _G ,
The auxiliary grid electrode 24 is connected to an auxiliary grid terminal _18SG via an auxiliary grid wiring 28.

[0017] On both ends of the substrate 12, the cathode terminal 18 a pair of filament support frame 30 having a _K are fixed respectively, between which the filament support frame 30, directly-heated cathode A thin filament 32 functioning as a wire is stretched so as to be at a predetermined height position parallel to the longitudinal direction of the substrate 12 and separated from the display surface of the substrate 12.

For this reason, the thermoelectrons emitted from the filament 32 are accelerated by the grid electrode 22 to which a positive voltage (acceleration voltage) of, for example, about 20 V is applied to the zero-volt filament 32. When a positive voltage is also applied to the phosphor layer 20 surrounded by the grid electrode 22, thermions collide with the phosphor layer 20 to cause the phosphor layer 20 to emit light. Even if a voltage is applied, if a negative bias voltage (cutoff bias) of about several volts is applied to the filament 32 to the grid electrode 22 surrounding the same, thermionic electrons reach the phosphor layer 20. The phosphor layer 20 does not emit light. Therefore, in the state where the thermoelectrons are emitted by the current flowing through the filament 32, the grid electrode 2
When a positive voltage is also applied to a desired one of the phosphor layers 20 _S , 20 _D , and 20 _N in synchronization with the sequential application of a positive voltage to the phosphor layer 2, a desired driving is performed by so-called dynamic driving. The light emission display is performed in the pattern shown in FIG.

Although a cut-off bias (negative erase voltage) is applied to the grid electrode 22 to which no acceleration voltage is applied, a common auxiliary grid electrode 24 is applied to, for example, the grid electrode 22. A positive voltage similar to the accelerating voltage is constantly applied to make the potential constant. For this reason, the negative electric field generated by the grid electrode 22 to which the cutoff bias is applied is canceled by the auxiliary grid electrode 24, and the electron flow toward the desired phosphor layers 20 _S , 20 _D , and 20 _N to emit light is reduced. Is not disturbed by the negative electric field, and uneven emission of the phosphor layer 20 is suitably suppressed.

Hereinafter, the fluorescent display tube 10 of the substrate 12 will be described.
2 showing an enlarged portion showing the phosphor layer 20 _S having the “8” character shape, which is one of the display patterns of FIG.
The electrode structure on the substrate 12 will be described in detail with reference to FIG. On the display surface of the substrate 12, an anode for printed wiring 34 is formed so as thick film conductor paste is connected to the anode terminal 18 _P by firing and are printed in the order of 15μm by the screen printing method, An insulator layer 38 formed to a predetermined thickness and appropriately provided with a through hole 36 penetrating in the thickness direction is fixed thereon. The insulator layer 38 is formed by applying a thick film insulating paste made of a low-melting glass and a coloring pigment to a thickness of about 30 to 40 μm by a screen printing method and firing it. The wiring 34 is
Instead of being provided by screen printing, for example, an aluminum thin film may be provided by etching.

On the insulator layer 38, the phosphor layer 20
A graphite layer 40 having a pattern similar to that of _S but having a slightly larger pattern is formed at a position where the graphite layer 40 is electrically connected to the anode printed wiring 34 via the through hole 36. The graphite layer 40 is formed by printing and firing a thick film paste containing graphite as a main component in a predetermined pattern with a thickness of about 40 μm, and functions as an anode of the display tube 10. In this embodiment, strictly speaking, the portion located below the phosphor layer 20 _S of the "8" character form of the graphite layer 40 serves as an anode, a phosphor layer 20 _S of the "8" character form The portion 42 protruding from the outer peripheral side functions as an outer peripheral electrode.

Then, the phosphor layer 20 _S is laminated on the graphite layer 40 by printing the thick film phosphor paste. Further, by thick film insulative paste is printed, the rib-shaped wall 44 of and conditions surrounding the it contacts the outer periphery of the phosphor layer 20 _S is erected on the graphite layer 40 at the same time, the An auxiliary rib-like wall 46 is in contact with and surrounds the outer peripheral edge of the graphite layer 40 and is spaced apart from the outer peripheral side of the rib-like wall 44 by a predetermined distance.
8 is erected. In the rib-shaped wall 44,
What is provided at the boundary of each adjacent segment,
In order to prevent a short circuit between the segments, as shown at the left end in FIG.
It is erected from 8.

The rib-like wall 44 and the auxiliary rib-like wall 46
, By thick film paste which is made of an insulating material such as low melting point glass or an inorganic filler by thick film printing is printed multiple times, than, for example, 150μm approximately phosphor layer 20 a width of _S 100 The ribs 44 and the auxiliary ribs 46 have an interval of, for example, about 150 μm. The rib-like wall 44 and the auxiliary rib-like wall 46
The top of the grid electrode 22 and the auxiliary grid electrode 2 are printed by thick-film conductor paste, respectively.
4 are formed simultaneously. These grid electrodes 2
2. The auxiliary grid electrode 24 is fixed with a particulate conductive material such as silver, palladium, copper, aluminum, nickel, and carbon with a thickness of 10 to 50 μm. The grid electrode 22 and the auxiliary grid electrode 24 are respectively connected to the grid terminal 18 _G and the auxiliary grid terminal via the grid wiring 26 and the auxiliary grid wiring 28 formed on the insulator layer 38 by thick film printing. Connected to 18 _SG .

According to the fluorescent display tube 10 configured as described above, the accelerating voltage is sequentially applied to each grid electrode 22 for display control, and the plurality of phosphor layers 20 are synchronized with the acceleration voltage.
_{When an} accelerating voltage is applied to any of _S , 20 _D and 20 _N to emit light through the graphite layer 40, thermions emitted from the filament 32 and accelerated by the grid electrode 22 emit, for example, fluorescent light. Body layer 20 _S
And illuminates it. At this time, in order to cancel the negative electric field generated by the grid electrode 22 to which the cut-off bias is applied and suppress the uneven light emission, the auxiliary rib-like wall 46 provided on the outer peripheral side of the rib-like wall 44 is provided at the top. A constant voltage is constantly applied to the auxiliary grid electrode 24. Therefore, when an acceleration voltage is applied to any of the grid electrodes 22, the auxiliary grid electrode 24 provided between the adjacent grid electrodes 22 has a negative electric field generated by the other grid electrode 22 to which the erase voltage is applied. Acts to cancel out.

As described above, the adjacent grid electrodes 22,
The auxiliary grid electrode 24 provided between the grid electrodes 22 is an auxiliary grid electrode 24 common to the grid electrodes 22 and 22.
Therefore, the auxiliary grid electrode 24 individually driven with the grid electrode 22 with respect to the grid electrode 22
It is no longer necessary to provide the grid electrodes 22 and 2
The number of the auxiliary grid electrodes 24 provided between the two can be set to the minimum number required to cancel the negative electric field generated by the grid electrode 22 to which the erasing voltage is applied, and in this embodiment, one. . Therefore, the distance d between the adjacent grid electrodes 22, which is necessary for providing the auxiliary grid electrode 24 and suppressing unevenness in light emission, is such that the width of the auxiliary rib-like wall 46 is W, the auxiliary rib-like wall 46 and the rib-like wall 4
4 is D (in this example, 150 μm
), W + 2D (that is, about 450 μm)
Thus, it is possible to obtain the fluorescent display tube 10 capable of reducing the light emitting pattern interval (for example, the interval between the “8” character shapes) without causing light emission unevenness.

Incidentally, in the conventional fluorescent display tube having the auxiliary grid electrode, as shown in FIG. 4, for example, the individual light emitting patterns are formed so that the grid electrode 22 surrounds the outer periphery of the rib-shaped wall 44 provided on the top. An independent auxiliary rib-like wall 48 is provided for each (for example, “8” character shape), and an auxiliary grid electrode 50 is provided on the top. Therefore, as shown in FIG. 5, each auxiliary grid electrode 5 is provided between the grid electrodes 22 of the adjacent light emitting pattern.
0 is provided, and the adjacent grid electrode 2
There has been a problem that the distance d between 2, 22 is relatively large, 2W + 3D (that is, about 750 μm).

That is, in the above-mentioned conventional fluorescent display tube, as shown in FIG. 4, the grid electrode 22 of each light emitting pattern and the auxiliary grid electrode 50 are connected by connecting electrodes 52 provided at a plurality of locations. It was driven integrally for each light emitting pattern. Therefore, when the fluorescent display tube is driven by the dynamic driving, when the light is emitted from any of the light emitting patterns, the current is supplied to the auxiliary grid electrode 50 located between the adjacent light emitting patterns, so that another cutoff bias is applied. In order to cancel the negative electric field generated by the grid electrode 22 to which the light is applied and suppress the uneven light emission, it is necessary to provide a sufficient number of auxiliary grid electrodes 50 to suppress the uneven light emission for each light emitting pattern. Thus, between the grid electrodes 22 of the adjacent light emitting patterns, the auxiliary grid electrodes 50 of twice as many as the minimum number required to suppress uneven light emission were provided.

On the other hand, the fluorescent display tube 10 of this embodiment
According to the above, as described above, the auxiliary grid electrode 24 is driven independently of the grid electrode 22 and is always supplied with a constant voltage, so that uneven light emission is suppressed between adjacent light emitting patterns. It is sufficient to provide only the minimum number required to perform the operation. The auxiliary grid electrode 24
, A constant voltage substantially the same as the acceleration voltage is always applied. However, since a cutoff bias is applied to the grid electrode surrounding the phosphor layer 20 that does not emit light, it is applied to the auxiliary grid electrode 24. Erroneous light emission of the phosphor layer 20 due to the applied voltage does not occur.

According to the present embodiment, the auxiliary rib-like wall 4
Reference numeral 6 denotes an auxiliary grid electrode 2 provided around each rib-shaped wall 44 and provided on the top of the auxiliary rib-shaped wall 46.
4 is connected to the common auxiliary grid wiring 28, so that the auxiliary grid electrode 50 as shown in FIGS.
The number of independent wirings and electrodes is minimized as compared with the conventional fluorescent display tube provided with (in the case of this embodiment, only one is increased), and wiring and driving circuits are complicated. Is suppressed.

Further, according to the present embodiment, the phosphor layer 20 _S
Is formed on the graphite layer 40 by screen printing on the graphite layer 40 surrounded by the rib-shaped wall 44 so that the inner wall surface and the outer peripheral edge of the rib-shaped wall 44 are in contact with each other. 20 _S is ribbed wall 4
Since no gaps are formed inside 4, the distance between the display patterns formed by the phosphor layers is reduced, and the display density can be further increased.

According to the present embodiment, the phosphor layer 20 _S
Is provided on the graphite layer 40 and the outer peripheral electrode 42 is provided on the outer periphery thereof, so that the substrate 12 outside the rib-like wall 44 is provided.
(Accurately, the insulator layer 38) The surface is prevented from being charged with negative charge, and light emission unevenness is further suppressed.

Next, another embodiment of the present invention will be described. In the following description, the same parts as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the embodiment shown in FIGS. 6 and 7, the graphite layer 40 is provided only inside the rib-like wall 44 in the above-described embodiment, and all the rib-like walls 44 are directly provided on the insulator layer 38. The other configuration is almost the same.

In the fluorescent display tube shown in FIGS. 6 and 7, the auxiliary grid electrode 24 provided on the auxiliary rib-shaped wall 46 is connected to the common auxiliary grid wiring 28 by being continuous over the entire surface of the fluorescent display tube. , A constant voltage is always applied, and the grid electrodes 22,
Since only one auxiliary grid electrode 24 is provided between the grid electrodes 22, the grid electrodes 22,
22 can be reduced.

Moreover, according to this embodiment, the phosphor layer 20
_Since the rib-like wall 44 surrounding _S is also provided directly on the insulator layer 38, all the rib-like walls 44 are formed of a thick film in which the inorganic frit is bonded by the low-melting glass binder, so that it is relatively strong. By projecting from the insulator layer 38, the rib-like wall 44 has a sufficient fixing strength, and is suitably prevented from falling off when an impact is applied.

In the embodiment shown in FIG. 8, on the insulator layer 38 of the fluorescent display tube, a plurality of phosphor layers 20 _M arranged in a matrix-like light-emitting pattern and a “REC” character-shaped light-emitting pattern are provided. A phosphor layer 20 _C representing the phosphor layer 20 _C and a phosphor layer 20 _I representing the light emission pattern in the form of an indicator are arranged, and the respective outer peripheral edges of the respective phosphor layers 20 _M , 20 _C and 20 _I are the same as in the above-described embodiment. Grid electrode 2 on top
2 are provided. An auxiliary rib-like wall 46 having the auxiliary grid electrode 24 at the top is provided at the boundary between the light emitting patterns. Even in this case, since the auxiliary grid electrode 24 is provided so as to surround each light-emitting pattern, the cut-off bias is applied to the grid electrode 22 provided for each light-emitting pattern when light is emitted from each light-emitting pattern by dynamic driving. The negative electric field generated by the application is canceled by the auxiliary grid electrode 24, and the light emission unevenness of any of the light emission patterns is suppressed.

That is, the auxiliary grid electrode 24 only needs to be provided for each unit of the light emitting pattern to which the acceleration voltage or the cut-off bias is applied at the same time as the dynamic driving is performed. It is set appropriately.

The embodiment shown in FIG. 9, "8" in the phosphor layer 20 _S character shape, between the grid electrode 22 and the auxiliary grid electrode 24, further second auxiliary grid for each "8" characters An electrode 54 is provided, which corresponds to the conventional fluorescent display tube shown in FIGS. 4 and 5 further provided with a common auxiliary grid electrode 24. That is, similarly to the conventional auxiliary grid electrode 50, the second auxiliary grid electrode 54 is provided with the second auxiliary grid electrode 54 erected along the outer peripheral edge of the rib-shaped wall 44.
It is provided along the outer peripheral edge of the grid electrode 22 on the top of the auxiliary rib-like wall 56 and is connected to the grid electrode 22 by connection electrodes 58 provided at a plurality of locations. Driven. Therefore, in the present embodiment, a total of three auxiliary grid electrodes 24 and the second auxiliary grid electrode 54 are provided between the grid electrodes 22 and 22 of the adjacent light-emitting patterns. Two of the three work effectively. When the acceleration voltage of the grid electrode 22 is low, or when the cutoff bias is high, a plurality of auxiliary grid electrodes may be required, and in such a case, for example, a configuration as in the present embodiment is employed. .

Accordingly, in this embodiment, the auxiliary grid electrodes are provided in a number equal to or more than the minimum number required to suppress the uneven light emission, and the interval between the grid electrodes 22 is made relatively large. However, also in this case, the auxiliary grid electrode 24 is
Since a common number of auxiliary grid electrodes are provided for each light emitting pattern, that is, two auxiliary grid electrodes are provided for each of the light emitting patterns, and the grid electrodes 22 and 22 are provided. Compared to the case where four are provided between the grid electrodes, the interval between the grid electrodes 22, 22 is smaller.

The embodiment shown in FIG. 10 shows a configuration example in which a plurality of (two) auxiliary grid electrodes are required as in the case of FIG. 9, but in this embodiment,
The second auxiliary grid electrode 56 provided on the inner peripheral side of the auxiliary grid electrode 24 is connected to the auxiliary grid electrode 24 by connection electrodes 58 provided at a plurality of locations. Therefore, the auxiliary grid electrodes 24 and 56 are common to the adjacent light-emitting patterns, and the number of auxiliary grid electrodes between the grid electrodes 22 and 22 of the adjacent light-emitting patterns is required to suppress uneven light emission. Is the minimum number. Therefore, according to the present embodiment, the grid electrode 2 is further compared with the embodiment shown in FIG.
The interval between 2, 22 can be reduced. That is,
The auxiliary grid electrodes 24 and 56 other than the grid electrode 22 provided so as to surround the phosphor layer 20 _S for each light emitting pattern for dynamic driving can be all common electrodes. It is desirable to do so in order to make the spacing of 22 as small as possible.

In the embodiment shown in FIG.
An auxiliary grid electrode 60 is provided between the plurality of “8” character-shaped phosphor layers 20 _S and the “m” character-shaped phosphor layer 20 _C. Are provided only in the vicinity of the boundary portion, and are not provided so as to surround these light emitting patterns. When the cutoff bias is applied to the grid electrode 22 adjacent to the light emitting pattern to emit light, the light emitting unevenness can occur mainly only in the vicinity of the boundary between the adjacent light emitting patterns. Therefore, if the light emitting unevenness can be sufficiently suppressed. For example, it is sufficient to provide only a partial auxiliary grid electrode 60.

While one embodiment of the present invention has been described with reference to the drawings, the present invention can be applied to other embodiments.

For example, in the above-described embodiment, the auxiliary grid electrode 24 is provided in common on the entire surface of the fluorescent display tube 10, but a plurality of auxiliary grid electrodes may be provided separately. In this case, the application of the voltage to the auxiliary grid electrode may be performed steadily, but may be configured to be appropriately turned on / off according to the scanning timing of the grid electrode 22.

Further, in the embodiment, the same positive voltage as that of the grid electrode 22 is applied to the auxiliary grid electrode 24 and the like, but the voltage applied to the auxiliary grid electrode 24 and the like is the acceleration voltage applied to the grid electrode 22. And according to the cut-off bias, it is set appropriately so as not to cause light emission unevenness,
For example, a positive voltage lower than the voltage applied to the grid electrode 22 may be applied. Further, it is not always necessary to apply a constant voltage.
2 may be changed in relation to the acceleration voltage or cutoff bias applied.

In the embodiment shown in FIGS. 9 and 10, the auxiliary grid electrode 24 and the second auxiliary grid electrode 54 are provided all around the grid electrode 22. When an acceleration voltage is applied to one grid electrode 22 of an adjacent light emitting pattern, the cutoff bias applied to the other grid electrode 22 is set so that light emission unevenness does not occur. It does not have to be provided all around. For example, it is also possible to partially provide the second auxiliary grid electrode 54 only at the boundary between adjacent light emitting patterns.

The above description is merely an embodiment of the present invention, and the present invention can be variously modified without departing from the gist of the present invention.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a fluorescent display tube according to an embodiment of the present invention.

FIG. 2 is a plan view showing a main part of a display surface of the substrate of the embodiment of FIG.

FIG. 3 is a sectional view of the embodiment in FIG.

FIG. 4 is a view corresponding to FIG. 2 showing a main part of a display surface of a substrate of a conventional fluorescent display tube.

FIG. 5 is a sectional view taken along line VV of the fluorescent display tube of FIG. 4;

FIG. 6 is a view corresponding to FIG. 2 showing a main part of a display surface of a substrate in another embodiment of the present invention.

7 is a sectional view taken along line VII-VII of the embodiment of FIG.

FIG. 8 is a view corresponding to FIG. 2 showing a main part of a display surface of a substrate according to still another embodiment of the present invention.

FIG. 9 is a view corresponding to FIG. 2 showing a main part of a display surface of a substrate according to still another embodiment of the present invention.

FIG. 10 is a view corresponding to FIG. 2 showing a main part of a display surface of a substrate according to still another embodiment of the present invention.

FIG. 11 is a view corresponding to FIG. 2 showing a main part of a display surface of a substrate according to still another embodiment of the present invention.

[Explanation of symbols]

 22: grid electrode 24: auxiliary grid electrode 44: rib-like wall 46: auxiliary rib-like wall

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Jun Mouri 2160, Yatsunami, Yasu-cho, Asakura-gun, Fukuoka Prefecture 2160 Kyushu Noritake Co., Ltd. (56) References JP-A-62-290050 (JP, A) JP-A-6-251732 (JP, A) JP-A-60-59639 (JP, A) JP-A-49-52965 (JP, A) JP-A-64-93034 (JP, A) Patent JP2873271 (JP, B2) (58) Fields surveyed (Int. Cl. ⁶ , DB name) H01J 31/08-31/24

Claims (1)

(57) [Claims] 1. A phosphor layer having a shape corresponding to a light emitting pattern is fixed on a plurality of anodes provided on a display surface of a substrate, and a rib-like shape is provided at a position surrounding the phosphor layer so as to be higher than the phosphor layer. A wall is projected, a grid electrode is provided on the top of the rib-like wall, and a predetermined phosphor layer is formed by controlling electrons generated from a cathode located above the display surface in the vacuum space by the grid electrode. In a fluorescent display tube of a type that emits light, an auxiliary rib-like wall having a height similar to that of the rib-like wall is protrudingly provided on an outer peripheral side of the rib-like wall, and a predetermined acceleration voltage is applied to a top of the auxiliary rib-like wall. A fluorescent display tube provided with an auxiliary grid electrode applied independently of the grid electrode.